Worm drive



Feb. 2, 1932. D. KENDALL ET AL WORM DRIVE Filed Dec. 5, 1928 2 Sheets-Sheet 1 INVENTORS OM W wanna 0.1m

Feb. 2, 1932. o. KENDALL ET AL 1,843,375

WORM DRIVE Fi1ed Dec. 5, -192a 2 Sheets-Sheet 2 25 .30 INVENTORS M W Au 0; MM

Patented Feb. 2, 1932 I UNIIEB STATES DAVID KENDALL AND WALTER n. KELLER, or ALLIANC oIIIo,IAssIGNoRs To ,THE ALLIANCE MACHINE COMPANY, OF ALLIANCE; 01110, A CORPORATIONOF oHIo worms or'worm wheels because the substitution of a worm wheel for-the spur gear not provided a true direction.

WORM n IvE This invention relates to worm drives and is particularly useful in connection with a ratchet mechanism,.such as is employed in certain types of cranes, although it has numerous other applications. 7

Certain cranes, as for example soaking pit cranes, must be provided with a'ratchet to prevent over-travel. The stiff leg of a soaking pit crane, for example, may actually lift the crane trolley from its rails after the stiff leg comes in .contact with the top of the ingot in case no slip mechanism in the raising and lowering drive of the stifi' leg is provi ed. In various other drives on cranes and like machinery a Worm gear has numer ous advantages over spur gear drives, In spur gear drives as heretofore employed on crane work two types of over-travel mecha nisms have been employed. In one type a large master gear is made in two parts,"one driving and one driven; one part being a ratchet member and the other part a pawl member. In the other type one member consists of a brake wheel, and a' diflerential brake band is anchored to the other member.

Both types of mechanism are cumbersome and inaccessible for inspection and repair. The first mentioned type is disadvantageous in that the pawl action depends on the action of non-adjustable springs and noisy in operation. The second type mechanism is difficult to properly adjust and constantly.

requires readjustment. Furthermore, there is posltlve drlve in either It has-heretofore been impractical to use a ratchet mechanism in connection with worm drives because of the necessity of maintaining accurate alignment for the worm Wheel and worm. The ratchet mechanisms would necessarily result 7 in an imperfect T mechanism, the worm Wheel-being always likely to get out of alignment. 1

7e provide a worm drive wherein the worm wheel is mounted on a sleeve and is restrained against axial movement. A shaft is extended through this sleeve and a ratchet I Application filed December 3,,1'928. Serial No. 'faaze.

ried by af'central spider 17 The spider'fits connection is provided between the sleeve This construction'is very and the shaft. compact and the Worm wheel is always held in alignment; The mechanism is quiet in operatiom'provides a positivedrive'in one direction,"is readily adj ustedso that the load at which slipping in theopposite' direction will occur maybe nic'ely'controlled, and may be readily incorporated in crane design as it requires a minimum of space. *In the accompanyingdrawings illustrating the present preferred embodiment of the invention, F igure. 1 is'a side elevation partly broken away of a worm drive embodying our in- Vention, r

' Figure 2 is a transverse section line II II ofFigure 1,

taken on the --Figure 3 is axview to enlarged scale a I portion of Figure 2, 1 f Figure 4: is an end view of the sleeve show-: ing the ratchet'teeth, and

Figure 5'is a developed view showingthe ratchet teeth ofthe sleeve and of thecoop crating ratchet member in engagement. 7 I Figure 1 shows aframe member 2 forming part of a'trolley structure, andserving as thelower half of a :housing andbea ring for the worm drive. Itris surmountedby a' housing 3 held in place by bolts l. A worm shaft. 5 having an integral worm 6 lies in the top ofthe housing 3. It is carried in bearings 7 and 8, which-bearings are mounted in shells 9 and 10. a The bearing 8 is a combined .1- 85 radial and thrust bearing. 7

Fast type; A brake drum 15 is mounted on theother end ofvthe shaft. 1

[,The worm 6 mesheswith a worm wheel. thetee'th: of which are formed on a rim .car-

over a sleeve1'18 and is connected thereto by a key19 sothat the worm wheel and the "sleeve must rotate together; g

- The sleeve 18 is' journaled-in roller-bean;

ings19 carried by'shells 20lying in openings formed in opposite sides of the housings 2 and 3. Covers 21 are provided for the shells and the covers and shells are held in place by cap screws 22.

The inner faces 23 of the shells 20 cooperate with thrust rings 2 1 to prevent axial movement of the worm wheel. The end faces of the hub of the spider 17 bear against the thrust rings 24.

The shaft to be driven is indicatedi at 25. Its end portion is reduced in diameterand extends through the sleeve 18.

A flanged collar 26 lies against a shoulder 27 on the shaft and is keyed to the shaft. A thrustv ring 28 lies between the collar and the left hand end face of the sleeve 18 as viewed in Figure 2. V V j Adjacentthe right hand end of the sleeve 18, as viewed in Figure 2, there is provided a bearing 29 for the end portion of the shaft 25. The right hand end faceof the sleeve 18 has ratchet teeth 30 formed thereon. The projecting end portion of the shaft is provided with a second sleeve .31- which is slid able on the shaft, but is splined'thereto by a key32. The'sleeve 31 has ratchet teeth 33 thereon cooperating with the ratchet teeth 30. The sleeve 31 is backed by a compressionspring 34, one end of which engages the rear face of the sleeve 81' and the other end of which engages a washer 35 backed by a castillated nut 36 on the end of the shaft 25.

The ratchet mechanism provides a posi tive drive in one direction and africti'onal drive in the reverse direction. When a given resistanceto rotation of the shaft 25 in the reverse direction is set upthe sleeve 31 slides outwardlybn the shaft 25 and the ratchet teeth 33 click over the ratchet teeth 30. Any chattering or vibration is confined to the ratchet partsand no misalignment of the worm wheel occurs, as its radial and thrust bearings are not subjected. to any load by reason of the ratchet action. 1

Oil tubes. 37 are provided for'the bearings 19. The sleeve 18 and" the bearing 29 are: drilled as indicated at 38 so that lubrication of the bearing 19-.will also serve to lubricate the shaft 25 at the'bearing 29.

We have illustrated and described the present preferred form of our invention, but it is not limited to this form as it may be otherwise embodied within the scope of the following claim We claim: w I U A'worm drive, comprising ahollow casing with openings in opposite walls thereof, a shell lying in each opening, a sleeve extending' through the'shells and ournaled therein, a worm wheel mounted 'on the; sleeve, the shells having inner faces forming thrust bearings for preventing axial displacement of the worm wheel, a shaft extending through the sleeve, a ratchet connection between'the sleeve and the shaft, and azthrust DAVID KENDALL. WALTER D. KELLER. 

